<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>后盾人</title>
    <style>
        @media only screen and (max-width:768px) {
            h1 {
                color: red;
            }
        }
    </style>
</head>

<body>
    <h1>houdunren.com</h1>
</body>

</html>